Occupational asthma is asthma that's caused or worsened by breathing in chemical fumes, gases, dust or other substances on the job. Like other types of asthma, occupational asthma can cause chest tightness, wheezing and shortness of breath.

When treated early, occupational asthma may be reversible. Long-term exposure to allergy-causing substances can cause worsening symptoms and lifelong asthma.

Treatment for occupational asthma is similar to treatment for other types of asthma, and it generally includes taking medications to reduce symptoms. But the only sure way to eliminate your symptoms and prevent lung damage due to occupational asthma is to avoid whatever's triggering it.

Occupational asthma symptoms are similar to those caused by other types of asthma. Signs and symptoms may include:

Wheezing, sometimes just at night

Coughing

Shortness of breath

Chest tightness

Other possible accompanying signs and symptoms may include:

Runny nose

Nasal congestion

Eye irritation and tearing

Occupational asthma symptoms depend on the substance you're exposed to, how long and how often you're exposed, and other factors. Your symptoms may:

Get worse as the workweek progresses, go away during weekends and vacations, and recur when you return to work.

Occur both at work and away from work.

Start as soon as you're exposed to an asthma-inducing substance at work or only after a period of regular exposure to the substance.

Continue after exposure is stopped. The longer you're exposed to the asthma-causing substance, the more likely you'll have long-lasting or permanent asthma symptoms.

Make an appointment to see a doctor if you have breathing problems, such as coughing, wheezing or shortness of breath. Breathing problems may be a sign of asthma, especially if symptoms seem to be getting worse over time or appear to be aggravated by specific triggers or irritants.

More than 300 workplace substances have been identified as possible causes of occupational asthma. These substances include:

Animal substances, such as proteins found in dander, hair, scales, fur, saliva and body wastes.

Chemicals, such as anhydrides, diisocyanates and acids used to make paints, varnishes, adhesives, laminates and soldering resin. Other examples include chemicals used to make insulation, packaging materials, and foam mattresses and upholstery.

Respiratory irritants, such as chlorine gas, sulfur dioxide and smoke.

Asthma symptoms start when your lungs become irritated (inflamed). Inflammation causes several reactions that restrict the airways, making breathing difficult. With occupational asthma, lung inflammation may be triggered by either an allergic response to a substance, which usually develops over time, or a lung irritation caused by an inhaled substance, such as chlorine, which may affect you immediately.

You're at increased risk of developing occupational asthma if:

You have existing allergies or asthma. Although this can increase your risk, many people who have allergies or asthma do jobs that expose them to lung irritants and never have symptoms.

Allergies or asthma runs in your family. Your parents may pass down a genetic predisposition to asthma.

You work around known asthma triggers. Some substances are known to be lung irritants and asthma triggers.

You smoke. Smoking increases your risk of developing asthma.

High-risk occupations

It's possible to develop occupational asthma in almost any workplace. But your risk is higher if you work in certain occupations. Here are some of the riskiest jobs and the asthma-producing substances associated with them:

The longer you're exposed to a substance that causes occupational asthma, the worse your symptoms will become — and the longer it will take for them to improve once you end your exposure to the irritant. In some cases, exposure to airborne asthma triggers can cause permanent lung changes and lifetime asthma symptoms.

You're likely to start by seeing your family doctor or a general practitioner. Or you may start by seeing a doctor who specializes in asthma (allergist-immunologist or pulmonologist).

Here's some information to help you prepare for your appointment.

What you can do

Be aware of any pre-appointment restrictions. When you make the appointment, ask if there's anything you need to do in advance. You may need to stop taking antihistamines if you're likely to have an allergy skin test.

Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.

Note the timing of your asthma symptoms — for example, note if your symptoms are worse at work and get better when you're away from work.

Make a list of all possible workplace lung irritants and anything else that seems to trigger your symptoms. You may want to take a look at the material safety data sheet (MSDS) for your work area, if there is one. Usually kept in a binder near your work area, this sheet lists toxic substances and irritants used on your job site. (Keep in mind, not all occupational asthma triggers are listed in the MSDS).

Write down key personal information, including major stresses or recent life changes and changes in your job or workplace.

Bring a list of all medications, vitamins or supplements you take.

Bring a family member or friend along, if possible. Someone who accompanies you may remember information you missed or forgot.

Is a workplace irritant a likely cause of my breathing problems or asthma flare-ups?

Other than the most likely cause, what are other possible causes for my symptoms or condition?

What tests do I need? Do these tests require any special preparation?

Is my condition likely temporary or chronic?

How do I treat occupational asthma? Do I have to quit my job?

What are the alternatives to the primary approach you're suggesting?

I have other health conditions. How can I best manage these conditions together?

Are there restrictions that I need to follow?

Should I see a specialist?

Is there a generic alternative to the medicine you're prescribing?

Are there brochures or other printed material I can take with me? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

When did you first notice your symptoms?

How severe are your symptoms?

Do you have breathing problems when you're away from work or only when you're on the job?

Have your symptoms been continuous, or do they come and go?

Have you been diagnosed with allergies or asthma?

What, if anything, seems to improve your symptoms?

Do allergies and asthma run in your family?

Are you exposed to fumes, gases, smoke, irritants, chemicals, or plant or animal substances at work? If so, how often and for how long?

Do you work in unusual environmental conditions, such as extreme heat, cold or dryness?

What, if anything, appears to worsen your symptoms?

Diagnosing occupational asthma is similar to diagnosing other types of asthma. However, your doctor will also try to identify whether a workplace irritant is causing your symptoms and what it may be.

An asthma diagnosis needs to be confirmed by tests that may include lung (pulmonary) function tests and an allergy skin prick test. He or she may order blood tests, X-rays or other tests to rule out a cause other than occupational asthma.

Testing your lung function

Your doctor may ask you to perform lung function tests. These include:

Spirometry. This noninvasive test, which measures how well you breathe, is the preferred test for diagnosing asthma. During this 10- to 15-minute test, you take deep breaths and forcefully exhale into a hose connected to a machine called a spirometer. If certain key measurements are below normal for a person your age and sex, your airways may be blocked by inflammation — a key sign of asthma.

Your doctor has you inhale a bronchodilator drug used in asthma treatment, then retake the spirometry test. If your measurements improve significantly, it's likely you have asthma.

Peak flow measurement. Your doctor may ask you to carry a peak flow meter, a small hand-held device that measures how fast you can force air out of your lungs. The slower you are able to exhale, the worse your condition. You'll likely be asked to use your peak flow meter at selected intervals during working and nonworking hours. If your breathing improves significantly when you're away from work, you may have occupational asthma.

Nitric oxide test. This test is used to see how much nitric oxide gas is in your breath. A high level of nitric oxide can be a sign of asthma.

Tests for specific lung irritants

Your doctor may do tests to see whether you have a reaction to specific substances. These include:

Allergy skin tests. Your skin is pricked with purified allergy extracts and observed for signs of an allergic reaction. These tests can't be used to diagnose chemical sensitivities but may be useful in evaluating sensitivity to animal dander, mold, dust mites and latex.

Challenge test. You inhale an aerosol containing a small amount of a suspected chemical to see if it triggers a reaction. Your lung function is tested before and after the aerosol is given to see whether it affects your ability to breathe.

Avoiding the workplace irritant that causes your symptoms is critical. However, once you become sensitive to a substance, tiny amounts may trigger asthma symptoms, even if you wear a mask or respirator. You may need medications to control your symptoms and prevent asthma attacks.

Treating asthma involves both preventing symptoms and treating an asthma attack in progress. The right medication for you depends on a number of things, including your age, symptoms, asthma triggers and what seems to work best to keep your asthma under control.

Long-term control medications

In most cases, these medications need to be taken daily. Types of long-term control medications include:

Inhaled corticosteroids. These medications include fluticasone (Flovent Diskus, Flovent HFA), budesonide (Pulmicort Flexhaler), mometasone (Asmanex), ciclesonide (Alvesco), beclomethasone (Qvar) and others. They are the most commonly prescribed long-term asthma medications. You may need to use these medications for several days to weeks before you achieve maximum benefit.

Inhaled corticosteroids have a relatively low risk of side effects and are generally safe for long-term use. A fungal infection in your mouth or throat is the most common side effect. You can usually prevent that by rinsing your mouth after inhaling these drugs.

Leukotriene modifiers. These oral medications include montelukast (Singulair), zafirlukast (Accolate) and zileuton (Zyflo CR). They help prevent asthma symptoms for up to 24 hours. In rare cases, montelukast has been linked to psychological reactions, such as agitation, aggression, hallucinations, depression and suicidal thinking. Seek medical advice right away for any unusual reaction.

Long-acting beta agonists (LABAs). These inhaled medications include salmeterol (Serevent Diskus) and formoterol (Foradil). LABAs open the airways and reduce inflammation. However, they've been linked to severe asthma attacks. LABAs should only be taken in combination with an inhaled corticosteroid.

Combination inhalers. Medicationssuch as fluticasone and salmeterol (Advair Diskus, Advair HFA), budesonide and formoterol (Symbicort), and mometasone and formoterol (Dulera), contain an LABA and a corticosteroid and may increase your risk of a severe asthma attack.

Theophylline. This is a daily pill that helps keep the airways open (bronchodilator). Theophylline (Theo-24, Elixophyllin, others) relaxes the muscles around the airways to make breathing easier. It's not used as often now as in past years because more-effective medications are available.

Quick-relief medications

Also called rescue medications, these are used as needed for rapid, short-term symptom relief during an asthma attack — or before exercise if your doctor recommends it. Types of quick-relief medications include:

Ipratropium (Atrovent HFA). This bronchodilator is used mainly for emphysema and chronic bronchitis, but it's sometimes used to treat asthma attacks.

Oral and intravenous corticosteroids. These medications relieve airway inflammation caused by severe asthma. Examples include prednisone and methylprednisolone (Medrol). When used long term, they can cause serious side effects, such as high blood pressure, weight gain and increased risk of infection, so they're used to treat severe asthma symptoms only on a short-term basis.

Treatment for allergy-induced asthma

If your asthma is triggered or worsened by allergies, you may benefit from allergy treatment as well. Allergy treatments include:

Allergy medications. These include oral and nasal spray antihistamines and decongestants as well as corticosteroid, cromolyn (NasalCrom) and ipratropium (Atrovent) nasal sprays.

Allergy shots (immunotherapy). Immunotherapy injections are generally given once a week for a few months, then once a month for a period of three to five years. Over time, they gradually reduce your immune reaction to specific allergens.

Omalizumab (Xolair). Given by injection, this is for difficult-to-control allergies and asthma.

Don't rely only on quick-relief medications

Long-term asthma control medications — such as inhaled corticosteroids — are the cornerstone of asthma treatment. These medications keep asthma under control on a day-to-day basis and make it less likely you'll have an asthma attack.

If you do have an asthma flare-up, a quick-relief inhaler can ease your symptoms right away. But if your long-term control medications are working properly, you shouldn't need to use your quick-relief inhaler very often.

Keep a record of how many puffs you use each week. If you need to use your quick-relief inhaler more often than your doctor recommends, see your doctor. You probably need to adjust your long-term control medication.

While many people claim alternative remedies reduce asthma symptoms, in most cases more research is needed to see if they work and if they have possible side effects, especially in people with allergies and asthma. A number of other alternative treatments have been tried for asthma, but there's no clear, proven benefit from treatments such as:

Breathing techniques. These include structured breathing programs such as the Buteyko method, the Papworth method, lung-muscle training and yoga breathing exercises (pranayama).

Acupuncture. This technique has roots in traditional Chinese medicine. It involves placing very thin needles at strategic points on your body. Acupuncture is safe and generally painless, but evidence for its use in asthma is inconclusive.

Relaxation techniques. Certain techniques — such as meditation, biofeedback, hypnosis and progressive muscle relaxation — may help with asthma by reducing tension and stress, though there's no clear evidence that it improves asthma.

Herbal remedies and dietary supplements. A number of herbal remedies and dietary supplements have been tried for asthma, including bitter orange, omega-3 fatty acids (found in fish oil and flaxseed) and vitamin C. Study results have been mixed.

Talk to your doctor before taking any herbs or supplements — some of these treatments may cause potentially dangerous side effects and may interact with other medications.

Although you may rely on medications to relieve symptoms and control inflammation associated with occupational asthma, you can do several things on your own to maintain overall health and lessen the possibility of attacks:

If you smoke, quit. In addition to all its other health benefits, being smoke-free may help prevent or lessen symptoms of occupational asthma.

Minimize household allergens. Common household substances — such as mold, pollen, dust mites and pet dander — can aggravate symptoms of occupational asthma. Air conditioners, dehumidifiers and thorough cleaning practices, especially in your bedroom, can minimize your exposure to these substances and help you breathe easier.

If you have a job in a high-risk profession, in the United States your company has legal responsibilities to help protect you from hazardous chemicals. Under guidelines established by the Occupational Safety and Health Administration (OSHA), your employer is required to do the following:

Inform you if you'll be working with any hazardous chemicals.

Train you how to safely handle these chemicals.

Train you how to respond to an emergency, such as a chemical spill.

Provide protective gear, such as masks and respirators.

Offer additional training if a new chemical is introduced to your workplace.

Under OSHA guidelines, your employer is required to keep a material safety data sheet (MSDS) for each hazardous chemical that's used in your workplace. This is a document that must be submitted by the chemical's manufacturer to your employer. You have a legal right to see and copy such documents. If you suspect you're allergic to a certain substance, show the material safety data sheet to your doctor.

While at work, be alert for unsafe and unhealthy working conditions and report them to your supervisor. If necessary, call OSHA at 800-321-OSHA (800-321-6742) and ask for an on-site inspection. You can do this so that your name won't be revealed to your employer.

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